Thanks for your interest in Syncfusion products.
Unfortunately we could not refer the image provided in your update since it is broken. We suspect that your requirement is to change the cell text and to resize the columns to fill the gridlistcontrol. To customize the cell text , QueryCellInfo event can be used and please refer the forum #127335 for this scenario. To resize the columns to fill the grid, AllowProportionalColumnSizing property can be used.
this.gridListControl1.Grid.AllowProportionalColumnSizing = true;
Please let us know if we misunderstood anything.